Twinning plays a pivotal role in strengthening titanium and its alloys, particularly at cryogenic temperatures, yet the factors controlling twin evolution and associated hardening mechanisms remain largely elusive. To tackle this problem, we combine electron backscattered diffraction (EBSD) with site-specific high-resolution nanoindentation mapping to correlatively investigate the cryogenically rolled titanium with tailored grain sizes, leveraging machine learning for large-scale data analysis. Characterization of ∼8000 twins confirms the existence of four types of twins in the deformed sample where {101¯2} twins and {112¯2} twins are the predominant ones. Twin density scales positively with grain size, as larger grains accommodate more twins and diverse variants. Grain orientation further governs twin selection and intragranular area fraction via the effective rolling Schmid factor. Correlative nanoindentation-EBSD mapping reveals that twinned regions outperform equiaxed grains in hardness, independent of orientation effects. Machine learning of these datasets delineates a hardening hierarchy of {112¯2} secondary twins > {112¯2} primary twins > {101¯2} twins>matrix. Dislocation characterization within twin regions indicates that the high hardening capacity of twins is attributed to the <c+a> dislocations in twins. These insights unravel the interplay of grain size, orientation, and twinning in cryogenic deformation, furnishing a microstructure-driven framework for optimizing mechanical performance of titanium alloys.
{"title":"Revealing Cryo-loading Induced Twinning and its Impact on Titanium via Correlative Data-driven Mechanomicroscopy","authors":"Xiao Liang, Hanqi Wang, Xichen Zhou, Qianyong Zhu, Cheng Zhang, Wenlong Xiao, Yiqian Guo, Zhen Li, Yu Liu, Peng Kang, Lei Zheng, Hongbo Guo, Shiteng Zhao","doi":"10.1016/j.actamat.2026.122137","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122137","url":null,"abstract":"Twinning plays a pivotal role in strengthening titanium and its alloys, particularly at cryogenic temperatures, yet the factors controlling twin evolution and associated hardening mechanisms remain largely elusive. To tackle this problem, we combine electron backscattered diffraction (EBSD) with site-specific high-resolution nanoindentation mapping to correlatively investigate the cryogenically rolled titanium with tailored grain sizes, leveraging machine learning for large-scale data analysis. Characterization of ∼8000 twins confirms the existence of four types of twins in the deformed sample where {10<mml:math altimg=\"si1.svg\"><mml:mover accent=\"true\"><mml:mn>1</mml:mn><mml:mo>¯</mml:mo></mml:mover></mml:math>2} twins and {11<mml:math altimg=\"si2.svg\"><mml:mover accent=\"true\"><mml:mn>2</mml:mn><mml:mo>¯</mml:mo></mml:mover></mml:math>2} twins are the predominant ones. Twin density scales positively with grain size, as larger grains accommodate more twins and diverse variants. Grain orientation further governs twin selection and intragranular area fraction via the effective rolling Schmid factor. Correlative nanoindentation-EBSD mapping reveals that twinned regions outperform equiaxed grains in hardness, independent of orientation effects. Machine learning of these datasets delineates a hardening hierarchy of {11<mml:math altimg=\"si2.svg\"><mml:mover accent=\"true\"><mml:mn>2</mml:mn><mml:mo>¯</mml:mo></mml:mover></mml:math>2} secondary twins > {11<mml:math altimg=\"si2.svg\"><mml:mover accent=\"true\"><mml:mn>2</mml:mn><mml:mo>¯</mml:mo></mml:mover></mml:math>2} primary twins > {10<mml:math altimg=\"si1.svg\"><mml:mover accent=\"true\"><mml:mn>1</mml:mn><mml:mo>¯</mml:mo></mml:mover></mml:math>2} twins>matrix. Dislocation characterization within twin regions indicates that the high hardening capacity of twins is attributed to the <c+a> dislocations in twins. These insights unravel the interplay of grain size, orientation, and twinning in cryogenic deformation, furnishing a microstructure-driven framework for optimizing mechanical performance of titanium alloys.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"1 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-16DOI: 10.1016/j.actamat.2026.122134
Martina Freund, Sang-Hyeok Lee, Peter Koch, Pei-Ling Sun, Zhuocheng Xie, Sandra Korte-Kerzel
The effect of off-stoichiometric alloying on the mechanical behaviour of the hexagonal C14 Ca-Mg-Al Laves phase was investigated through a combined atomistic modelling and experimental approach. Atomistic simulations were used to explore the compositional space and characterise the resulting transitions in elastic and plastic properties. The calculations reveal that partial substitution of Mg by Ca significantly reduces elastic stiffness and unstable stacking fault energies, indicating enhanced dislocation mobility in Ca enriched compositions. A ternary C14 Ca37Mg61Al2 phase was synthesised and analysed to validate these predictions. Nanoindentation yielded an average hardness of 2.4 ± 0.3 GPa and modulus of 50.0 ± 1.9 GPa, representing a ∼32% hardness reduction relative to binary Ca31Mg69. Slip trace analy-sis and transmission electron microscopy confirmed dominant non-basal deformation involving prismatic and pyramidal ⟨a⟩ dislocations, as well as the occurrence of cross-slip. The agreement between simulations and experiments demonstrates that the enrichment with larger Ca atoms induces lattice dilation and facilitates dislocation activity. This compositional softening mechanism provides a route to tune the plasticity of Laves phases through controlled off-stoichiometric alloying.
{"title":"Compositional softening and non-basal slip in off-stoichiometric Ca–Mg–Al C14 Laves phases","authors":"Martina Freund, Sang-Hyeok Lee, Peter Koch, Pei-Ling Sun, Zhuocheng Xie, Sandra Korte-Kerzel","doi":"10.1016/j.actamat.2026.122134","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122134","url":null,"abstract":"The effect of off-stoichiometric alloying on the mechanical behaviour of the hexagonal <ce:italic>C</ce:italic>14 Ca-Mg-Al Laves phase was investigated through a combined atomistic modelling and experimental approach. Atomistic simulations were used to explore the compositional space and characterise the resulting transitions in elastic and plastic properties. The calculations reveal that partial substitution of Mg by Ca significantly reduces elastic stiffness and unstable stacking fault energies, indicating enhanced dislocation mobility in Ca enriched compositions. A ternary <ce:italic>C</ce:italic>14 Ca<ce:inf loc=\"post\">37</ce:inf>Mg<ce:inf loc=\"post\">61</ce:inf>Al<ce:inf loc=\"post\">2</ce:inf> phase was synthesised and analysed to validate these predictions. Nanoindentation yielded an average hardness of 2.4 ± 0.3 GPa and modulus of 50.0 ± 1.9 GPa, representing a ∼32% hardness reduction relative to binary Ca<ce:inf loc=\"post\">31</ce:inf>Mg<ce:inf loc=\"post\">69</ce:inf>. Slip trace analy-sis and transmission electron microscopy confirmed dominant non-basal deformation involving prismatic and pyramidal ⟨<mml:math altimg=\"si12.svg\"><mml:mi>a</mml:mi></mml:math>⟩ dislocations, as well as the occurrence of cross-slip. The agreement between simulations and experiments demonstrates that the enrichment with larger Ca atoms induces lattice dilation and facilitates dislocation activity. This compositional softening mechanism provides a route to tune the plasticity of Laves phases through controlled off-stoichiometric alloying.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"38 1","pages":"122134"},"PeriodicalIF":9.4,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-16DOI: 10.1016/j.actamat.2026.122129
Yue Li, Lei Wang, Zhijun Wang, Junjie Li, Jincheng Wang
Phase coarsening kinetics at finite volume fractions (ϕ≠0) are strongly affected by multi-particle diffusional interactions. Although effective-medium approaches extend classical Lifshitz–Slyozov–Wagner theory to account for such interactions in a mean-field manner, their predictive capability has long been limited by the difficulty of determining an appropriate characteristic diffusion length. In this work, a global constraint is proposed to overcome this limitation. The central idea is to approximate the unique concentration field in the real matrix by a linear superposition of single-particle concentration fields defined in the effective-medium framework, motivated by the microscopic description of the multi-particle diffusion problem. This approximation naturally requires the total solute content of the superposed field to be identical to that of the real matrix, thereby enabling a statistically consistent determination of the characteristic diffusion length. The resulting asymptotic solutions recover the classical ϕ scaling in the dilute limit (ϕ→0) and quantitatively capture the accelerated coarsening kinetics in the dense limit (ϕ→1), showing good agreement with numerical simulations over a wide range of volume fractions.
{"title":"Effective-medium descriptions on phase coarsening: A statistical global constraint capturing multi-particle diffusional interactions","authors":"Yue Li, Lei Wang, Zhijun Wang, Junjie Li, Jincheng Wang","doi":"10.1016/j.actamat.2026.122129","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122129","url":null,"abstract":"Phase coarsening kinetics at finite volume fractions (<mml:math altimg=\"si1.svg\" display=\"inline\"><mml:mrow><mml:mi>ϕ</mml:mi><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">≠</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:math>) are strongly affected by multi-particle diffusional interactions. Although effective-medium approaches extend classical Lifshitz–Slyozov–Wagner theory to account for such interactions in a mean-field manner, their predictive capability has long been limited by the difficulty of determining an appropriate characteristic diffusion length. In this work, a global constraint is proposed to overcome this limitation. The central idea is to approximate the unique concentration field in the real matrix by a linear superposition of single-particle concentration fields defined in the effective-medium framework, motivated by the microscopic description of the multi-particle diffusion problem. This approximation naturally requires the total solute content of the superposed field to be identical to that of the real matrix, thereby enabling a statistically consistent determination of the characteristic diffusion length. The resulting asymptotic solutions recover the classical <mml:math altimg=\"si2.svg\" display=\"inline\"><mml:msqrt><mml:mrow><mml:mi>ϕ</mml:mi></mml:mrow></mml:msqrt></mml:math> scaling in the dilute limit (<mml:math altimg=\"si3.svg\" display=\"inline\"><mml:mrow><mml:mi>ϕ</mml:mi><mml:mo>→</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:math>) and quantitatively capture the accelerated coarsening kinetics in the dense limit (<mml:math altimg=\"si4.svg\" display=\"inline\"><mml:mrow><mml:mi>ϕ</mml:mi><mml:mo>→</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math>), showing good agreement with numerical simulations over a wide range of volume fractions.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"59 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-15DOI: 10.1016/j.actamat.2026.122127
Yandi Jia, Yingjie Ma, Rongpei Shi, Hao Wang, Kui Du, Yujing Yang, Qian Wang, Sensen Huang, Min Qi, Yingying Shen, Jinmin Liu, Jiafeng Lei, Rui Yang
The strength–ductility trade-off remains a central challenge in structural titanium alloys. While heterogeneous microstructure design is a promising solution, existing strategies rely on single metastable phase refinement. Here, we demonstrate a novel paradigm in a Ti-3Al-5Mo-4.5V (wt.%) alloy by synergistically activating dual metastable phase refinement pathways—ω-assisted α nucleation and α″ decomposition—for the first time. This approach successfully fabricates a four-scale heterogeneous α (FSH-α) microstructure, comprising micron-scale primary αp alongside three distinct secondary α morphologies: micron-scale αs-fine, nanoscale αs-ultra, and ladder-like αs-ladder. Advanced characterization reveals that αs-ultra forms via ω-assisted nucleation, while αs-fine and αs-ladder evolve from the decomposition of α″, with the latter originating from α″ with lattice distortion regions. Compared to the conventional annealed microstructure and two-scale heterogeneous α (TSH-α) microstructure refined solely through ω-assisted αs-ultra nucleation, the FSH-α structure exhibits a superior yield strength (990–1050 MPa vs. 820–850 MPa and 880–970 MPa) without sacrificing ductility (11–16% elongation vs. 12–15% and 14–18%). This enhancement stems from hetero-deformation induced (HDI) strengthening due to a multi-tiered network of hetero-interface, where plastically deformable αs-fine domains act as mechanical buffers, generating additional HDI stress while coordinating strain to maintain ductility. This work establishes a transformative strategy for designing hierarchical heterostructures by harnessing the synergy of multiple phase transformations to overcome property trade-offs in α + β titanium alloys.
{"title":"Four-scale Hierarchical α Microstructure via ω and α″ Synergistic Refinement: Overcoming Strength–Ductility Trade-off in an α + β Ti-alloy","authors":"Yandi Jia, Yingjie Ma, Rongpei Shi, Hao Wang, Kui Du, Yujing Yang, Qian Wang, Sensen Huang, Min Qi, Yingying Shen, Jinmin Liu, Jiafeng Lei, Rui Yang","doi":"10.1016/j.actamat.2026.122127","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122127","url":null,"abstract":"The strength–ductility trade-off remains a central challenge in structural titanium alloys. While heterogeneous microstructure design is a promising solution, existing strategies rely on single metastable phase refinement. Here, we demonstrate a novel paradigm in a Ti-3Al-5Mo-4.5V (wt.%) alloy by <ce:bold>synergistically activating dual metastable phase refinement pathways</ce:bold>—ω-assisted α nucleation and α″ decomposition—<ce:italic>for the first time</ce:italic>. This approach successfully fabricates a four-scale heterogeneous α (FSH-α) microstructure, comprising micron-scale primary α<ce:inf loc=\"post\">p</ce:inf> alongside three distinct secondary α morphologies: micron-scale α<ce:inf loc=\"post\">s-fine</ce:inf>, nanoscale α<ce:inf loc=\"post\">s-ultra</ce:inf>, and ladder-like α<ce:inf loc=\"post\">s-ladder</ce:inf>. Advanced characterization reveals that α<ce:inf loc=\"post\">s-ultra</ce:inf> forms via ω-assisted nucleation, while α<ce:inf loc=\"post\">s-fine</ce:inf> and α<ce:inf loc=\"post\">s-ladder</ce:inf> evolve from the decomposition of α″, with the latter originating from α″ with lattice distortion regions. Compared to the conventional annealed microstructure and two-scale heterogeneous α (TSH-α) microstructure refined solely through ω-assisted α<ce:inf loc=\"post\">s-ultra</ce:inf> nucleation, the FSH-α structure exhibits a superior yield strength (990–1050 MPa vs. 820–850 MPa and 880–970 MPa) without sacrificing ductility (11–16% elongation vs. 12–15% and 14–18%). This enhancement stems from hetero-deformation induced (HDI) strengthening due to a multi-tiered network of hetero-interface, where plastically deformable α<ce:inf loc=\"post\">s-fine</ce:inf> domains act as mechanical buffers, generating additional HDI stress while coordinating strain to maintain ductility. This work establishes a transformative strategy for designing hierarchical heterostructures by harnessing the synergy of multiple phase transformations to overcome property trade-offs in α + β titanium alloys.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"13 1","pages":"122127"},"PeriodicalIF":9.4,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-15DOI: 10.1016/j.actamat.2026.122130
Rei Yano, Masaki Tanaka, Shigeto Yamasaki, Tatsuya Morikawa, Tomohito Tsuru
In order to elucidate the influence of the athermal omega phase (ωath) and solute V on the thermally activated process of dislocation glide in β-titanium alloys of Ti–17V and Ti–22V, the values of effective shear stress, activation volume and activation enthalpy were obtained by tensile tests and strain-rate jump tests at various temperatures. Effective shear stresses showed a strong temperature dependence, indicating that yielding is controlled by a thermally activated process of dislocation glide. The temperature dependence of the activation enthalpy suggested that the process of overcoming the Peierls potential controls the dislocation glide below Ttrans, while interaction with ωath or solute V is possibly dominant above Ttrans. It was found that the shearing of ωath or the interaction with its coherent stress fields are unlikely to be dominant for the thermally activated process of dislocation glide, because the CRSS for the shearing of ωath is much smaller than the experimental value and the activation volumes estimated for the coherent stress fields are significantly larger than those obtained experimentally. Interaction with a single solute V atom is also unlikely to be dominant because the estimated activation volumes are significantly smaller than the experimentally evaluated values. The interaction between dislocation and several solute V atoms is expected to be reasonable for the thermally activated process for dislocation glide above Ttrans.
{"title":"Thermally activated process of dislocation glide in Ti–17V and Ti–22V alloys","authors":"Rei Yano, Masaki Tanaka, Shigeto Yamasaki, Tatsuya Morikawa, Tomohito Tsuru","doi":"10.1016/j.actamat.2026.122130","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122130","url":null,"abstract":"In order to elucidate the influence of the athermal omega phase (ω<ce:inf loc=\"post\">ath</ce:inf>) and solute V on the thermally activated process of dislocation glide in β-titanium alloys of Ti–17V and Ti–22V, the values of effective shear stress, activation volume and activation enthalpy were obtained by tensile tests and strain-rate jump tests at various temperatures. Effective shear stresses showed a strong temperature dependence, indicating that yielding is controlled by a thermally activated process of dislocation glide. The temperature dependence of the activation enthalpy suggested that the process of overcoming the Peierls potential controls the dislocation glide below <ce:italic>T</ce:italic><ce:inf loc=\"post\">trans</ce:inf>, while interaction with ω<ce:inf loc=\"post\">ath</ce:inf> or solute V is possibly dominant above <ce:italic>T</ce:italic><ce:inf loc=\"post\">trans</ce:inf>. It was found that the shearing of ω<ce:inf loc=\"post\">ath</ce:inf> or the interaction with its coherent stress fields are unlikely to be dominant for the thermally activated process of dislocation glide, because the CRSS for the shearing of ω<ce:inf loc=\"post\">ath</ce:inf> is much smaller than the experimental value and the activation volumes estimated for the coherent stress fields are significantly larger than those obtained experimentally. Interaction with a single solute V atom is also unlikely to be dominant because the estimated activation volumes are significantly smaller than the experimentally evaluated values. The interaction between dislocation and several solute V atoms is expected to be reasonable for the thermally activated process for dislocation glide above <ce:italic>T</ce:italic><ce:inf loc=\"post\">trans</ce:inf>.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"13 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147465314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mechanical field control in powder bed fusion is critical in mitigating distortion and cracking by reducing residual stresses, and enhancing mechanical properties by regulating dislocation structures. However, achieving these while preserving optimal melt region dimensions for desired build quality and microstructures remains challenging due to the inherent positive correlations among input energy, melt region and heat-affected zone (HAZ) dimensions, and residual stresses and strains. This study establishes a framework for effectively manipulating residual stresses and strains in melt region and HAZ, on the premise of preserving melt depth with error margins <8%. Through thermomechanical analyses and experimental validations, we investigate the effects of melting strategies and heat accumulation on residual stress–strain constitutive behaviors. Although conventional strategies such as shortening beam path length or spot melting are commonly employed to reduce residual stresses, we reveal their limited effectiveness under typical conditions where heat accumulates. In contrast, we propose the concept of equivalent infinite cooling time interval, based on which the real-spot (RS) melting strategy can significantly reduce macroscopic residual stresses. The underlying mechanisms are elucidated by revealing the dual effect of heat accumulation on residual stresses and strains, which induces a trade-off between their peak levels and total affected areas. Moreover, we demonstrate that the RS melting strategy alleviates continuous compressive plastic deformation in melt region and HAZ by reshaping principal plastic strain orientations and alternating compressive and tensile plastic strain components. This enables reducing residual stresses while increasing cumulative plastic strains, thereby overcoming the limitations in mechanical field control imposed by the positive correlation between residual stresses and strains.
{"title":"Mechanical Field Control in Electron Beam Powder Bed Fusion: Dual Effect of Heat Accumulation and Melting Strategies based on Equivalent Infinite Cooling Time Interval","authors":"Yuchao Lei, Yufan Zhao, Kenta Yamanaka, Yi Zhang, Xin Lin, Akihiko Chiba","doi":"10.1016/j.actamat.2026.122125","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122125","url":null,"abstract":"Mechanical field control in powder bed fusion is critical in mitigating distortion and cracking by reducing residual stresses, and enhancing mechanical properties by regulating dislocation structures. However, achieving these while preserving optimal melt region dimensions for desired build quality and microstructures remains challenging due to the inherent positive correlations among input energy, melt region and heat-affected zone (HAZ) dimensions, and residual stresses and strains. This study establishes a framework for effectively manipulating residual stresses and strains in melt region and HAZ, on the premise of preserving melt depth with error margins <8%. Through thermomechanical analyses and experimental validations, we investigate the effects of melting strategies and heat accumulation on residual stress–strain constitutive behaviors. Although conventional strategies such as shortening beam path length or spot melting are commonly employed to reduce residual stresses, we reveal their limited effectiveness under typical conditions where heat accumulates. In contrast, we propose the concept of equivalent infinite cooling time interval, based on which the real-spot (RS) melting strategy can significantly reduce macroscopic residual stresses. The underlying mechanisms are elucidated by revealing the dual effect of heat accumulation on residual stresses and strains, which induces a trade-off between their peak levels and total affected areas. Moreover, we demonstrate that the RS melting strategy alleviates continuous compressive plastic deformation in melt region and HAZ by reshaping principal plastic strain orientations and alternating compressive and tensile plastic strain components. This enables reducing residual stresses while increasing cumulative plastic strains, thereby overcoming the limitations in mechanical field control imposed by the positive correlation between residual stresses and strains.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"31 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147447153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-14DOI: 10.1016/j.actamat.2026.122120
Luciano Borasi, Steven E. Kooi, Christopher A. Schuh
{"title":"Crossing from thermally activated to drag-controlled plasticity in mild steel as strain rate increases","authors":"Luciano Borasi, Steven E. Kooi, Christopher A. Schuh","doi":"10.1016/j.actamat.2026.122120","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122120","url":null,"abstract":"","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"16 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147448377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-14DOI: 10.1016/j.actamat.2026.122121
Haoliang Xiang, Yue Wu, Dean Liu, Bin Li, Xiaofen Li, Wei Wu, Yue Zhao
The introduction of a transient liquid phase into industrial pulsed laser deposition (PLD) systems has enabled the ultrahigh-rate growth of superconducting films (≥ 100 nm s−1), allowing opportunities for cost-effective, large-scale fabrication of second-generation high-temperature superconducting tapes. However, the growth mechanism of superconducting films under ultrahigh-rate industrial PLD conditions remains unclear. Here, a statistical investigation of industrial samples is conducted and a plate-like orthorhombic BaCu3O4 phase is identified for the first time on the EuBa2Cu3O7−δ (EuBCO) surface, which shows strong correlation with its superconducting performance. Comprehensive characterization reveals that BaCu3O4 is an epitaxially stabilized intermediate phase. Notably, BaCu3O4 plays a key role in the high-rate epitaxial growth of EuBCO by reacting with the Y/Eu species that migrate to the growth front, forming superconducting phases — a mechanism further supported by the formation of oriented YBa2Cu3O7−δ. Based on these results, a growth model is proposed whereby the epitaxial BaCu3O4 intermediate phase serves as a crucial reactant, driving the formation of c-axis-oriented EuBCO in transient liquid-assisted growth. This work provides novel insights into the underlying mechanisms of transient liquid-assisted growth in PLD-grown REBa2Cu3O7−δ films and establishes a framework for further optimization of industrial PLD processes.
在工业脉冲激光沉积（PLD）系统中引入瞬态液相，使得超导薄膜（≥100 nm s - 1）的超高速率生长成为可能，从而为第二代高温超导带的大规模制造提供了经济高效的机会。然而，超高速工业PLD条件下超导薄膜的生长机制尚不清楚。本文通过对工业样品的统计研究，首次在EuBa2Cu3O7−δ (EuBCO)表面发现了一种类似板状的正交相，该相与其超导性能有很强的相关性。综合表征表明BaCu3O4是外延稳定的中间相。值得注意的是，BaCu3O4通过与迁移到生长前沿的Y/Eu物质反应形成超导相，在EuBCO的高速率外延生长中发挥了关键作用，这一机制得到了YBa2Cu3O7−δ取向形成的进一步支持。基于这些结果，提出了一种生长模型，其中外延BaCu3O4中间相作为关键的反应物，在瞬态液体辅助生长中驱动c轴取向EuBCO的形成。这项工作为PLD生长的REBa2Cu3O7−δ薄膜的瞬态液体辅助生长的潜在机制提供了新的见解，并为进一步优化工业PLD工艺建立了框架。
{"title":"Observation and Role of Epitaxial BaCu3O4 Phase in Ultrahigh-Rate EuBa2Cu3O7−δ Film Growth via Industrial Pulsed Laser Deposition","authors":"Haoliang Xiang, Yue Wu, Dean Liu, Bin Li, Xiaofen Li, Wei Wu, Yue Zhao","doi":"10.1016/j.actamat.2026.122121","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122121","url":null,"abstract":"The introduction of a transient liquid phase into industrial pulsed laser deposition (PLD) systems has enabled the ultrahigh-rate growth of superconducting films (≥ 100 nm s<sup>−1</sup>), allowing opportunities for cost-effective, large-scale fabrication of second-generation high-temperature superconducting tapes. However, the growth mechanism of superconducting films under ultrahigh-rate industrial PLD conditions remains unclear. Here, a statistical investigation of industrial samples is conducted and a plate-like orthorhombic BaCu<sub>3</sub>O<sub>4</sub> phase is identified for the first time on the EuBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−</sub><em><sub>δ</sub></em> (EuBCO) surface, which shows strong correlation with its superconducting performance. Comprehensive characterization reveals that BaCu<sub>3</sub>O<sub>4</sub> is an epitaxially stabilized intermediate phase. Notably, BaCu<sub>3</sub>O<sub>4</sub> plays a key role in the high-rate epitaxial growth of EuBCO by reacting with the Y/Eu species that migrate to the growth front, forming superconducting phases — a mechanism further supported by the formation of oriented YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−</sub><em><sub>δ</sub></em>. Based on these results, a growth model is proposed whereby the epitaxial BaCu<sub>3</sub>O<sub>4</sub> intermediate phase serves as a crucial reactant, driving the formation of <em>c</em>-axis-oriented EuBCO in transient liquid-assisted growth. This work provides novel insights into the underlying mechanisms of transient liquid-assisted growth in PLD-grown REBa<sub>2</sub>Cu<sub>3</sub>O<sub>7−</sub><em><sub>δ</sub></em> films and establishes a framework for further optimization of industrial PLD processes.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"44 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147447476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-14DOI: 10.1016/j.actamat.2026.122126
Soumya Bandyopadhyay, Sourav Chatterjee, Dallas R. Trinkle, Richard G. Hennig, Victoria Miller, Michael S. Kesler, Michael R. Tonks
Applied magnetic fields can alter phase equilibria and kinetics in steels; however, quantitatively resolving how magnetic, chemical, and elastic driving forces jointly influence the microstructure remains challenging. We develop a quantitative magneto-mechanically coupled phase-field model for the Fe-C system that couples a CALPHAD-based chemical free energy with demagnetization-field magnetostatics and microelasticity. The model reproduces single- and multi-particle evolution during the inverse transformation at 1023 K under external fields up to 20 T, including ellipsoidal morphologies observed experimentally at 8 T. Chemically driven growth is isotropic; a magnetic interaction introduces an anisotropic driving force that elongates precipitates along the field into ellipsoids, while elastic coherency promotes faceting, yielding elongated cuboidal or “brick-like” particles under combined magneto-elastic coupling. Growth kinetics increase with C content, and decrease with field strength and misfit strain. Multi-particle simulations reveal dipolar interaction-mediated coalescence for field-parallel neighbors and ripening for field-perpendicular neighbors. Incorporating field-dependent diffusivity from experiment slows kinetics as expected; a first-principles-motivated anisotropic diffusivity correction is estimated to be small (2%). These results establish a process-structure link for magnetically assisted heat treatments of Fe-C alloys and provide guidance for microstructure control via chemo-magneto-mechanical synergism.
{"title":"Effect of magneto-mechanical synergism in the process-structure correlation in Fe-C alloys: A phase-field modeling approach","authors":"Soumya Bandyopadhyay, Sourav Chatterjee, Dallas R. Trinkle, Richard G. Hennig, Victoria Miller, Michael S. Kesler, Michael R. Tonks","doi":"10.1016/j.actamat.2026.122126","DOIUrl":"https://doi.org/10.1016/j.actamat.2026.122126","url":null,"abstract":"Applied magnetic fields can alter phase equilibria and kinetics in steels; however, quantitatively resolving how magnetic, chemical, and elastic driving forces jointly influence the microstructure remains challenging. We develop a quantitative magneto-mechanically coupled phase-field model for the Fe-C system that couples a CALPHAD-based chemical free energy with demagnetization-field magnetostatics and microelasticity. The model reproduces single- and multi-particle evolution during the <span><math><mrow is=\"true\"><mi is=\"true\">α</mi><mo is=\"true\">→</mo><mi is=\"true\">γ</mi></mrow></math></span> inverse transformation at 1023 K under external fields up to 20 T, including ellipsoidal morphologies observed experimentally at 8 T. Chemically driven growth is isotropic; a magnetic interaction introduces an anisotropic driving force that elongates <span><math><mi is=\"true\">γ</mi></math></span> precipitates along the field into ellipsoids, while elastic coherency promotes faceting, yielding elongated cuboidal or “brick-like” particles under combined magneto-elastic coupling. Growth kinetics increase with C content, and decrease with field strength and misfit strain. Multi-particle simulations reveal dipolar interaction-mediated coalescence for field-parallel neighbors and ripening for field-perpendicular neighbors. Incorporating field-dependent diffusivity from experiment slows kinetics as expected; a first-principles-motivated anisotropic diffusivity correction is estimated to be small (<span><math><mo is=\"true\"><</mo></math></span>2%). These results establish a process-structure link for magnetically assisted heat treatments of Fe-C alloys and provide guidance for microstructure control via chemo-magneto-mechanical synergism.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"34 1","pages":""},"PeriodicalIF":9.4,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147447167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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